Add REffectBuilder (#470)

kotlin-react/src/main/kotlin/react/REffectBuilder.kt

@@ -0,0 +1,34 @@
+@file:Suppress("NOTHING_TO_INLINE")
+
+package react
+
+// TODO: make external in IR
+class REffectBuilder
+private constructor() {
+    inline fun cleanup(
+        noinline block: RCleanup,
+    ) {
+        asDynamic().push(block)
+    }
+}
+
+internal fun useEffectCallback(
+    effect: REffectBuilder.() -> Unit,
+): () -> RCleanup? =
+    useCallback(effect) {
+        val cleanups = arrayOf<RCleanup>()
+        effect(cleanups.unsafeCast<REffectBuilder>())
+        buildCleanup(cleanups)
+    }
+
+private fun buildCleanup(
+    cleanups: Array<out RCleanup>,
+): RCleanup? {
+    if (cleanups.isEmpty())
+        return undefined
+
+    return {
+        for (cleanup in cleanups)
+            cleanup()
+    }
+}